This invention relates to a method of filling and sealing a container with a product, and more particularly, to a method of producing a package in which the integrity of the seal is preserved and voids within the container are virtually eliminated.
Prior methods for filling and sealing a container have provided a substantial "headspace" within the container in order that the seal area of the container is not contaminated with the product, which will result in incomplete and leaking seals.
This headspace gas hinders exploitation of sterilizable containers, because of the difficulty of accurately controlling the pressure within the containers during temperature changes, to ensure the seals are not ruptured or containers otherwise deformed or damaged. If the headspace gas is air, this will cause spoilage of oxygen-sensitive products.
This headspace also has the appearance of a partially filled container, giving a poor value impression to the consumer.
Additionally, the headspace allows movement of product during shipment, resulting in stressing of the lid material (which may rupture), and also damage to the product.
It is well known to use a diaphragm of stretchable lid material to close a container which is deformed to eliminate headspace. This stretchable lid material, however, typically is not puncture resistant and, hence, requires some secondary protection to maximize quality control of the product.